Electric translating circuit



July 13, 1943.

as AMR EDA/VIEW ZEAMP.

Fig. 2.

S. BECKER ELECTRIC TRANSLATING CIRCUIT Filed June 23, 1938 2Sheets-Sheet 1 fdc Fig.3.

Inventor": shew/art Becker,

y His Attorney.

v ELEC'TRIC' TRANSLATING cIRcu i'T Filed June 23, 1938 '2 Sheets-Sheet 2Stewart Becker,

His At torney.

Patented July 13, 1943 ELECTRIC TEANSLATIN G CIRCUIT Stewart Becker,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application June 23, 1938, Serial No. 215,427

2 Claims.

My invention relates to an improved electric translating circuit andmore particularly to a translating circuit having a controllabletransmission characteristic. While not limited thereto, my invention isparticularly suited for employment in signalling systems where thetransmission of a signalling voltage must be controlled in a manner tolimit the maximum amplitude of the voltage to a predetermined value.

An object of my invention is to provide an electric translating circuitin which the transmission of positive or negative or both positive andnegative peaks of an alternating current potential is controlled and islimited to a predetermined maximum value.

Another object of my invention is to provide an electric translatingcircuit which may couple tandem connected stages of signal amplifiersand my invention contemplates the control of an energy source includedin the translating circuit for the purpose of controlling and limitingto a predetermined value the maximum signal amplitude transferredthrough the translating circuit. As thus employed, an importantadvantage of my invention lies in the elimination of transient signalpeaks caused by extraneous noise sources. In the operation of myinvention, such transient signal peaks are limited to the predeterminedamplitude to which the transmission characteristic of my translatingcircuit has been adjusted which is generally that of the maximumamplitude of a signal oscillation.

A further object of my invention is to provide a translatory oscillatorcircuit whose generated oscillations have a rectangular wave form and anamplitude which may be varied at will to be either symmetrical orunsymmetrical in any degree about a zero amplitude axis.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization and method of operation,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which Fig. 1 illustrates my inventionas embodied in an electric power translating circuit used to connect asupply source to a load source, Figs. 2, 3, 4 and 8 are curves whichmore fully explain the operation of my invention, and Figs. 5 to 7inclusive illustrate embodiments of my invention as employed insignalling circuits.

Referring more particularly to Fig. 1 of the drawing, my invention isillustrated in an electric power translating circuit used to connect asupply source I0, I! and a load circuit l2, l3. A transformer l5 has aprimary M which is connected to the supply sourc H], II and has asecondary winding 16 connected to energize a unidirectional currentconducting path comprised by a unidirectional current conducting deviceH, a resistor 8, and a selectable portion of a voltage divider resistor9. The device I! is connected with a polarity such that the current flowis always in the direction from the point a through this device to thepoint d.

The resistor l8 and the lower half of the voltage divider resistance |9below the movable contact 20 are connected in a second unidirectionalcurrent conducting path comprised by a unidirectional current conductingdevice 2| and the primary 22 of a transformer 23. The device 2| isconnected with a polarity such that current flow-is always in adirection from the point 0 through this device to the point d. Thetransformer 23 is provided with a secondary winding 24 connected tosupply energy to the load circuit l2, IS.

A source 25 of unidirectional current is connected across the entirevoltage divider resistance I9 with a polarity, as indicated by thedrawing, such that a portion of the voltage Ede of the source 25,determined by the particular setting of the movable contact 20 along theresistance i9, produces a unidirectional current flow through each ofthe devices I! and 2| and through the resistor l8.

The operation of my translating circuit will now be explained by the aidof Figs. 2, 3 and 4 of the drawings. Assume as an initial condition thatthe supply source H], H is deenergized. The potential Ede appearingacross the lower portion of the resistor l9, by virtue of its connectionto the source of unidirectional potential 25, produces a current in bothcircuits and 2, these currents, of course, flowing in the same directionin resistance IS. The voltage Ede is represented in Fig. 2 by the curveEde.

Now assume that the supply source H], II is energized. The alternatingpotential E16 (Fig. 2) induced in the secondary winding N5 of thetransformer l5 combines with the unidirectional potential Ede to producein circuit l a voltage which is represented by curve E1 of Fig. 2.Since, as represented in 'Fig. 2, the potential E1 has a peak value inexcess of the voltage Ede, it overcomes this unidirectional voltageduring th time of the alternate peaks t1t2 when the two voltages oppose.During this time t1t2 no current the current I1 (flowing in circuit Iunder the influence of the voltage E1), which is of the form of curve E1limited to zero value during the time t1t2, combines with the voltageEde to produce a voltage in circuit 2 which may b represented by curveE2 of Fig. 3. During the time of the peaks t3t4 not previously limited,the voltage drop across resistance l8 overcomes the voltage Ede andtends to reverse the current in the circuit 2. This is prevented,however, by the unilateral property of device 2! with the result thatduring this time no current flows. Thus, both peaksare limited to avalue predetermined by the voltage Ede and irrespective of the magnitudeof the impressed voltage, the voltage supplied to the output cannotexceed a value corresponding tothis predetermined value. The current 12which flows in the circuit 2 as a result of the potential E2 is shown inFig. 4. This current, which is symmetrical about an average current 1'2represented by the broken line of Fig. 4, is supplied through thetransformer 23 to a load device connected to the load circuit I2, I3.

Fig. 5 represents an embodiment of my invention as employed in asignalling apparatus for which it is especially well suited. In thisarrangement, signal oscillations are supplied by an antenna groundsystem 26, 2? to signalling apparatus represented conventionally by therectangle 28, That portion of the signalling ap-- paratus includedwithin the rectangle 28 may comprise tunable elements by which theapparatus is tuned to respond to a desired signal frequency, a converterby which the signal frequency is transformed to an intermediatefrequency, and may also include as many stages of radio frequency andintermediate frequency amplification as desired.

T The output of the apparatus represented by the rectangle 28 is coupledby a transformer 29, having a primary winding 39 and a secondary winding3| inductively related and tuned by the respective condensers 32 and 33to the intermediate frequency, to an anode 3 3 of an electron dischargedevice 35.

I The modulation components of the signal oscil-. lations are impressedas a unidirectional potential across the diode load resistor 36 and arecoupled through a condenser 31 and resistor 38 to the control grid 39 ofthe electron discharge device 35. The condensers 40 and 4! are employedto by-pass radio frequency potentials around the'grid 39. The cathodebiasing resistor 42 and by-pass condenser 43 maintain the grid 39' at asuitable negative operating potential. The anode A5 of the electrondischarge device 35 is connected through a resistor 46 to a source ofpositive potential 41 which is maintained at ground potential foralternating currents by a condenser 48. p v

The audio frequency output of the electron discharge device 35 issupplied by a condenser 49 to a translating circuit of the general typeillustrated by Fig; 1 of the drawings. The unidirectional currentconducting devices H and 2| of 1 take the form, in the presentembodiment,

sistor 5?.

of an electron discharge device 59 having a pair of anodes 5!, 52 and apair of cathodes 53, 54. The anode 5| is connected to the couplingcondenser 49 and through a resistor 55 to the movable contact 53 of avoltage divider whose resistance 5? is connected between the positiveterminal ll of the high voltage source and ground. The cathodes 53 and54 are connected together and through a resistor 58 to ground. The anode52 of the electron discharge device 50 is connected to an outputcoupling condenser 59 and through a resistor 66 to the movable contact56 of the voltage divider. A condenser 6! is employed to maintain themovable contact 56 at ground potential with respect to alternatingcurrents. The condenser 59 is connected to the control grid 62 of anelectron discharge device 63 whose elements are connected inconventional manner to constitute a stage of audio frequencyamplification. The output of the electron discharge device 63 issupplied through an output transformer B l to a translating device 85which may be a loud speaker.

The operation of this embodiment of my invention will now be explained,Modulated signal oscillations are received on the antenna ground system26, 2?, are amplified, converted to an intermediate frequency, and arefurther amplified at the intermediate frequency by the apparatusconventionally represented by the rectangle 28. The signals thusamplified are supplied through the intermediate frequency transformer 29to the diode anode 34 of the electron discharge device 35 where thesignal oscillations are rectified and the audio frequency components ofthe signal oscillations appear across the resistor 33. This audiofrequency potential is supplied to the voltage divider resistor 38 and aselectable portion of the voltage appearing across the resistor 33 istransferred to the grid 39 of the electron discharge device 35 forfurther amplification.

The output of the electron discharge device 35 is coupled by thecondenser 49 to the translating circuit embodying my invention which issimilar in form to and operates in the manner of the arrangement of Fig.l. The movable contact 56 is adjusted along the Voltage divider resistor51 to impress a unidirectional potential'on the anodes El and 52 of thedevice 59, this potential normally having a value such that a minutecurrent flows from the anode 5i to the cathode 53 of the device 59 atthe instant when the maximum amplitude of an audio frequency signaloscillation is supplied through the condenser 49. This adjustment of themovable contact 56 in sures that the entire audio frequency cycle atmaximum amplitude will be transferred to the audio frequency amplifier63 yet limits transient noise oscillation peaks appearing in the audiofrequency to the maximum amplitude of a signal oscillation as determinedby the setting of the movable contact 56 on the voltage divider re-Thus, while the audio component of the modulated signal oscillation isfaithfully reproduced by the translating device 65, sharp peaks of noisehaving intensity greater than the value determined by the movablecontact 56 in its adjusted position on the voltage divider resistor 57are eliminated. If desired, the movable contact 56 may bemechanicallyconnected to operate with the movable contact provided onthe voltage divider 38 since the maximum amplitude of signaloscillations passing through my translating circuit varies directly inproportion to the setting of the contact on the voltage divider 38.

K Figs. 6 and 7 illustrate my invention as embodied in an oscillator forproducing oscillations having a square-topped or rectangular wave form.In Fig. 6, an electron discharge device 66 has an anode #2, a grid H anda cathode i5 suitably energized and connected with certain elements toconstitute an oscillator for generating oscillations of substantiallysinusoidal wave form. The frequency of the generated oscillations isdetermined by the tuned tank circuit 6! comprised by a variablecapacitor 68 and an inductance 59. The upper terminal of the inductance68 is connected through a condenser it! to the grid element H includedin the device 65 while the lower terminal of the inductance is connectedto the anode 12. Anode potential is supplied from a source of spacecurrent, not shown but Whose negative terminal is grounded and whosepositive terminal is connected to a conductor I3, through the lower halfof the inductance 69 to the anode 12. for currents of radio frequencythe cathode 75 of the device 66 to an intermediate tap on the inductance69 yet prevents the direct current in the conductor 13 from flowingdirectly to the cathode and thereby to ground. A resistor 76 incombination with the condenser It] impresses a suitable negativeoperating potential upon the grid H of the electron discharge device 5E.

Oscillations of sinusoidal wave form generated by the electrol dischargedevice 66 and its associated circuit elements are supplied through acondenser 16 to a wave form changing circuit where their wave form ischanged to a rectangular wave form and where the amplitude of thepositive and negative half cycles is controlled at will to control therectangular shape of the wave form. This wave form changing circuit iscomprised by an electron discharge device Ti whose anodes I8 and 19 arerespectively connected through resistors 88 and 8| to the movablecontact 82 of a voltage divider 83. The voltage divider 83 is connectedbetween the conductor 73 and ground. The cathodes 84 and 85 of theelectron discharge device 'l'? are connected together and through acommon resistor 86 to ground. Oscillations of changed wave formappearing across the resistor 8| are supplied through a condenser 81 toa pair of output terminals 88 where the oscillations of changed waveform may be supplied to other signalling apparatus, not shown. 5'

The operation of this rectangular wave form generator will now beexplained by reference to the curves of Fig. 8. Oscillations ofsubstantially sinusoidal wave form, represented in Fig. 8 by the brokencurve e, are generated by the electron discharge device 66 andassociated circuit elements. These sinusoidal oscillations are suppliedthrough the condenser 16 to the wave form changing circuit comprised bythe electron discharge device H and associated circuit elements whichoperate much in the manner of the translating circuit shown connectedbetween the tandem stages of audio frequency amplification in thearrangement of Fig. 5. The operation of the present arrangement differs,however, from that or the Fig. 5 circuit in that the amplitude of thesinusoidal oscillations supplied through the condenser i6 is preferablymade quite large and only the lower portions of the sinusoidaloscillations are allowed to pass to the output terminals 53. of thuscutting off the upper portion of the positive and negative half cyclesof the sinusoidal oscillations is to produce at the output terminals 88oscillations having a substantially rectangular wave form represented bythe solid line E of Fig.

A blocking condenser 14 effectively connects The eiTect 8. The amplitudeof the positive and negative half cycles of the potential E may becontrolled by adjustment of the position of the movable contact 82 alongthe voltage divider 83. The potential E oscillates in a symmetricalmanner about the zero amplitude axis 8i of Fig. 8.

The oscillator arrangement of Fig. 7 is similar to that of Fig. 6 exceptthat the amplitude of the positive and negative half cycles of potentialsupplied to the output terminals 88 may be individually controlled atwill in order that the potential E may be made symmetrical ornon-symmetrical about the zero amplitude axis Gil as desired. Elementsin this figure corresponding to like elements of Fig. 6 are designatedby like reference characters. In this embodiment of my invention, thepotential supplied to the anode 18 of the electron discharge device TIis controlled by a first voltage divider 83 while the potential suppliedto the anode I9 is independently controlled by the provision of a secondvoltage divider 89. This allows the amplitude of the positive andnegative half cycles of the voltage E to be varied at will thereby tocontrol the symmetry or lack of symmetry of the voltage E about the axis00. It will be evident that with this arrangement, either the negativeor the positive half cycles of the potential E may be reduced to zero ifdesired without affecting the wave form of the remaining half cycle ofpotential.

While I have shown in the arrangements of Figs. 1 and 5 a single sourceof unidirectional potential connected to supply current through each ofthe unidirectional conducting devices, it will be understood that thisis by way of illustration only and that individual sources ofunidirectional potential may be supplied for each of the unidirectionalcurrent conducting devices in the manner of Fig. 7. Where individualsources are employed, individual voltage dividers are preferably usedwith a single source in the manner of the Fig. 7 circuit to control theportion of the total potential of the source which it is desired tointroduce into each unidirectional current conducting path, and it willbe clear from the above description that one such path controls themaximum amplitude of the positive half cycle while the other pathcontrols the maximum amplitude of the negative half cycle of voltage orcurrent appearing in the load or output circuit.

While I have shown particular embodiments of my invention, it will ofcourse be understood that I do not wish to be limited thereto since manymodifications may be made both in the mechanical arrangement and theinstrumentalities employed, and I, therefore, contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A static eliminator having, in combination with a receiving system, acondenser connected with the receiving system, a tube having a cathodeand an anode and connected with the condenser so that signals receivedby the receiving system shall be transmitted through the condenser andthe tube in the direction from the cathode towards the anode for apositive half wave and from the anode towards the cathode for a negativehalf wave, a potentiometer, means for connecting the positive terminalof the potentiometer to the anode, means for connecting the negativeterminal of the potentiometer to the cathode,

wave and from the anode towards the cathode for a negative half wave, apotentiometer, tworesistors, means for connecting the positive terminalof the potentiometer through one of the resistors to the anode, meansfor connecting the negative terminal of the potentiomter through theother resistor to the cathode, and means for adjusting the potentiometerto maintain the anode positive with respect to the cathode to a degreeless than the Voltage corresponding to the static to be eliminated fromthe signals.

STEWART BECKER.

